The Research And Development Of Polishing System For Free-form Surfaces Based On 6 DOF Robot

Free-form surface has been applied widely in many fields such as mould,automobile,aerospace,ship and etc.At present finish processing such as grinding and polishing for free-form surface is done artificially.There are some drawbacks during in polishing artificially,that include lower efficiency,expensive processing cost,wicked processing environment of solid grain and lacking of systematic controlling method of surface quality for depending on operators' skill and experience.It not only improves polishing efficiency and polishing quality,but also relieves works' workload immensely.It devotes itself to develop the polishing system for free-form surface based on 6 DOF robot,what includes following work.(1)It proposes a kind of comprehensive sampling strategy based on curvature and local surface size factors;finishes dispersing curved surfaces applying 2D Mesher of UG/CAE;and extracts the coordinate and normal vector of mesh kont to be multi-axis CL.It proposes modified Dijkstra algorithm based on the list to plan polishing path,and fits polishing motion path using segmented lines.(2)It realizes the function of calibrating work coordinate for parts with general curved surfaces by Six Points Method,and proposes a new method of Eight Points(plane feature with three points,line feature with two points,rotating feature with three points)to calibrate work coordinate with rotating feature.Then it finishes compensating the length and radius of polishing tool using geometric method.(3)It develops force controlling system based on position controlling system of 6 DOF robotto realize robot force/position mixed controlling,and proposes a rational strategy for constant force polishing to abtain ideal polishing quality,efficiency and tool life.(4)It finishes developing the system for generating polishing data off-line named WHUT-CLGenerator system through VC++6.0 and UG,that realizes following functions such as dispersing curved surfaces,solving multi-axis CL points,planning polishing trajectory,printing polishing data and etc;and finishes developing the polishing controlling system with 6 DOF robot named WHUT-ROPOLISH to realize functions of I/O communication,initialize settings,tool compensation,calibrating work coordinate,polishing motion controlling and etc.(5)It generates the polishing data off-line by applying WHUT-CLGenerator system,then simulates and tests the validity of polishing track and reachability of every multi-axis CL point applying ROBCAD.Lastly it finishes constructing an experimental platform of robot polishing system,and takes the mould of a kind of carafes to polishing experiment applying WHUT-ROPOLISH system,that proves feasibility and surface quality skill of the robot polishing system successfully.It has finished developing basic functions of curved surfaces controlling system based on 6 DOF robot including generating multi-axis CL,planning polishing trajectory,calibrating work coordinate,tool compensation and controlling polishing motion,which can undertake the task for polishing curved surfaces automatically.